Geometry of phase-separated domains in phospholipid bilayers by diffraction-contrast electron microscopy.
Geometry of phase-separated domains in phospholipid bilayers by diffraction-contrast electron microscopy.
复制标题
通过衍射对比电子显微镜观察磷脂双层中相分离域的几何形状。
DOI：
10.1016/s0006-3495(81)84857-6
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发表时间：
1981
影响因子：
3.4
通讯作者：
Hui,SW
中科院分区：
文献类型：
--
作者：
Hui,SW
用低剂量衍射-衬度电子显微镜直接观察了二月桂酰磷脂酰胆碱/二棕榈酰磷脂酰胆碱（DLPC/DPPC）（1：1）和磷脂酰丝氨酸（PS）/DPPC（1：2）的水合分子双层中固相（凝胶）相区的大小和形状。双层的温度和湿度由设置在电子显微镜中的环境室控制。结晶域之间的对比度通过双层的衍射图案的电子光学滤波来增强。域被视为在双层的平面中的拼凑物，具有0.2-0.5微米的平均宽度。在不同温度下从衍射对比显微照片测量的固相线面积的百分比一般与已知相图所描绘的一致。域的形状和大小类似于在多层囊泡中通过冷冻断裂所看到的那些。温度相关的变化，在域的大小和相边界每单位面积更明显的不太混溶的DLPC/DPPC混合物。在PS/DPPC混合物中没有发现这些几何参数随温度的显著变化。利用分子衍射信号对结构域进行作图，不仅证实了相分离过程中不同分子堆积区域的存在，而且提供了对脂质双层结构边界和缺陷的定量测量。
The sizes and shapes of solidus (gel) phase domains in the hydrated molecular bilayers of dilauroylphosphatidylcholine/dipalmitoylphasphatidylcholine (DLPC/DPPC) (1:1) and phosphatidylserine (PS)/DPPC (1:2) are visualized directly by low dose diffraction-contrast electron microscopy. The temperature and humidity of the bilayers are controlled by an environmental chamber set in an electron microscope. The contrast between crystalline domains is enhanced by electron optical filtering of the diffraction patterns of the bilayers. The domains are seen as a patchwork in the plane of the bilayer, with an average width of 0.2–0.5 micrometer. The percentage of solidus area measured from diffraction-contrast micrographs at various temperatures agrees in general with those depicted by known phase diagrams. The shape and size of the domains resemble those seen by freeze-fracture in multilamellar vesicles. Temperature-related changes in domain size and in phase boundary per unit area are more pronounced in the less miscible DLPC/DPPC mixture. No significant change in these geometric parameters with temperature is found in the PS/DPPC mixture. Mapping domains by their molecular diffraction signals not only verifies the existance of areas of different molecular packing during phase separation but also provides a quantitative measurement of structural boundaries and defects in lipid bilayers.